The Spatial And Temporal Characteristics Of Blur Adaptation
Vidhya Subramanian · OhioLink ETD Center (Ohio Library and Information Network) · 2009
myopes watched television with their correction in one of the sessions and without in the other.Following the 90 minutes, visual acuity, refractive error and lens thickness were measured.They found a statistically significant two-letter improvement in vision after the session without spectacles that was not accompanied by a change in refractive error or lens thickness.They concluded that the change in acuity in the absence of a refractive shift suggested a sensory adaptation to blur.Mon-Williams et al (1998) conducted a similar study where they also looked at the contrast sensitivity function.In the first experiment of their two-part study they induced 1.00D myopia in 15 emmetropic subjects and measured visual acuity both monocularly and binocularly following a 30 min adaptation period.In the second experiment they introduced 2.00D of myopia, the subjects were cyclopleged and viewed the stimuli through an artificial pupil while the non-tested eye was covered.Both contrast sensitivity and visual acuity were measured during this session.In both the experiments they found a significant improvement in visual acuity following adaptation to optical defocus.They found an improvement in monocular visual acuity from logMAR 0.362 to 0.242 in the right eye and logMAR 0.366 to 0.272 in the left eye (i.e.approximately one line improvement in both eyes) following 30 minutes of adaptation to +1.00D of myopic blur.The CSF demonstrated a decrease in contrast sensitivity at mid-spatial frequencies (5 -25 cpd) and little or no effect at low and high frequencies following blur adaptation.They proposed that the reduced midspatial frequency sensitivity along with improvement in letter acuity is due to a masking of high frequency components in the image by low spatial frequency components during prolonged exposure to blur.This leads to decreases in the sensitivity of low frequencyselective channels resulting in improved resolution after the adaptation period.However